AN UNUSUAL ANIONIC OXO(MU-OXO)-VANADIUM(V) NETWORK INTERLINKED BY CATIONIC SODIUM CHAINS

The new compound 1-cyano-2-hydroxyprop-1-enyl)pyridine-2-carboxylic ac id (H(2)L) has been prepared and the structure of its ethyl ester dete rmined. The salt NaHL reacted with VO2+ to form the vanadium(v) comple x [Na(MeOH)(2)][VO(2)L]. Crystal-structure analysis of the complex rev ealed octahedral co-ordination of both the sodium and vanadium ions. V anadium is co-ordinated to enolate oxygen, carboxylate oxygen, pyridin e nitrogen, and two doubly bonded oxo groups in cis positions. The six th position is occupied by the oxo group of a neighbouring vanadium ce ntre at a rather long distance of 2.214(2) Angstrom. Anionic, asymmetr ically ore-bridged vanadium chains are thus formed. These are interlin ked by cationic sodium chains with sodium bonded to two bridging metha nols, the cyano nitrogen of one of the vanadate chains and the co-ordi nated carboxylate of the alternate vanadate chain. The network is furt her stabilized by hydrogen bonds. The relevance of the complex to biog enic vanadium compounds is discussed.